Business, science and entertainment applications depend upon computers to process and record data, often with large volumes of the data being stored or transferred to nonvolatile storage media. The non-volatile storage media typically includes magnetic discs, magnetic tape cartridges, optical disk cartridges, floppy diskettes, or floptical diskettes. The advantages of storing data on non-volatile storage media are numerous, including: a capability of storing hundreds of megabytes or even gigabytes of data (additional cartridges can be used to store still more data); providing a vehicle for long term storage and archival; backing up that data which resides on non-removable media; and providing a convenient vehicle for transferring data between computers. Typically, magnetic tape media is the most economical means of storing or archiving the data.
The amounts of data stored, accessed and processed by computers has increased as the computing power of the internal processors has increased. Hence, storage technology is continually pushed to increase storage capacities (as well as storage reliability). Improvements in storage densities in magnetic storage mediums, for example, has come in many areas including improved medium materials, improved error correction techniques, and decreased bit sizes. The amount of data stored on half inch magnetic tape, for example, has increased from megabytes of data stored on nine data tracks to gigabytes of data stored on 128 tracks of data.
The improvement in data densities on magnetic storage media, is due in large part to improvements made in the transducer used for reading and writing data to the magnetic storage medium. A major improvement in transducer technology has been realized with the magneto-resistive (MR) transducer developed by the IBM corporation. The MR transducer detects magnetic field signals as resistance changes in an MR stripe. Data densities can be increased using an MR transducer because signal levels for the MR transducer are typically much higher than for conventional inductive read heads. Furthermore, the output of the MR transducer depends only on the instantaneous magnetic field from the media and is independent of media velocity or time rate of change of the sensed fields.
Magnetic tape (and to some extent magnetic disks) is passed very near or directly over the MR transducer for reading data therefrom and writing data thereto. A buildup of static charge on the media, if allowed, could cause single or double bit failures, or worst could damage the sensitive MR transducer, thereby unacceptably reducing reliability. In the past, low resistive magnetic tape media, such as chromium-oxide magnetic tape, allowed static charge buildup to bleed off through the tape housing or at other points along the tape path. The inventors of the present invention have discovered, however, that higher resistivity media, for example, metal particle media, under certain atmospheric conditions, does not allow sufficient bleed off of static charge buildup.
Thus, what is needed is a MR transducer having protection for effectively discharging static charge buildup.